1. Field of the Invention
The present invention relates to a light-amount control device for controlling the amount of light emitted towards subjects to be photographed by silver-halide film cameras, digital cameras, cellular phones, and other devices with photographing functions.
2. Description of the Related Art
Recently, a smaller amount of light than before is required for illuminating objects, with a lighting apparatus, because of improvements in sensitivity of silver-halide films, color films, and CCDs. Therefore, even though the amount of light output by LEDs is smaller than that output by conventional xenon tubes, usage of LEDs as a lighting apparatus for photographing is proposed for improved lighting efficiency, reduced power consumption, and increased life.
However, because a single LED can not emit enough light for photographing, an apparatus including a plurality of LEDs as light sources, is proposed.
In the case where light is emitted for photographing, it is ideal that the entire photographing area of the camera is uniformly illuminated. However, because of a characteristic of the photographing lens known as the cosine fourth law, the luminance at the periphery of the photographing area becomes dark when the entire photographing area is uniformly illuminated.